As the power conversion industry matures and the cost of energy increases, manufacturers of uninterruptible power supplies (UPS), renewable energy power converters and motor drives have been challenged by market demands to provide products with higher conversion efficiencies, higher reliability and lower cost per kilowatt. Thirty years ago many large commercial power converters were based on low frequency SCR (silicon controlled rectifier) and thyristor based topologies. These were replaced by 2-level, half-bridge, higher frequency, pulse modulated IGBT (insulated gate bipolar transistor) based topologies. In the last few years, the industry has seen the emergence of 3-level neutral point clamp, and higher level IGBT based topologies previously used only in high power, medium-voltage applications. The invention potentially approaches the same performance as that of a multi-level inverter topology with an infinite number of DC levels. When compared to all prior art power conversion topologies in on-line UPS applications, the invention provides higher conversion efficiencies, higher reliability and lower cost.